In the five days since his almost-victory in the Iowa caucuses, Rick Santorum's critics have tried out an unusual line of attack against the former Pennsylvania senator. Not content with the many targets that Santorum's record presents, they've gone after the way he and his wife, Karen, handled the premature delivery and death of their fourth child, Gabriel, in 1996.

At 19 weeks of pregnancy, Gabriel was found to have a potentially fatal fetal abnormality. After a risky intrauterine surgery, Karen Santorum came down with an infection that ended up triggering labor. The baby lived for just two hours, and after his death the couple took his body home overnight — so that their children could "absorb and understand that they had a brother," Santorum said later — before burying him the following day.

This tragedy was old news until Santorum's Iowa surprise, at which point various commentators began to bring it up as evidence of his extremism and hypocrisy. Alan Colmes, Fox News's token liberal, cited Santorum's decision to take his son's body home as one of the crazier of all the "crazy things he's said and done," and The Washington Post's Eugene Robinson presented it as evidence that Santorum isn't just "a little weird, he's really weird." A number of left-wing Web sites, meanwhile, asserted that the antibiotics Santorum's wife had taken induced delivery before the fetus could survive outside the womb, which they argued was tantamount to the kind of late-term abortion Santorum famously opposes.

Neither attack made much sense. Weirdness is in the eye of the beholder, but as Commentary's Pete Wehner pointed out, at least one major pregnancy Web site advises parents of stillborn children to do roughly what the Santorums did.

But if the attacks on the Santorums' personal choices were incoherent (so incoherent, in fact, that both Colmes and Robinson soon backtracked), they were also entirely characteristic of our moment.

In a sense, one could say that these kinds of invasive debates become inevitable once the traditional zone of privacy around public figures collapses. But it would be more accurate to say that the zone of privacy has collapsed precisely because of the deep moral divisions that these kinds of controversies reveal.

Privacy is a luxury of moral consensus. Nobody would have thought to politicize the premature birth and death of John F. Kennedy's son Patrick, because abortion wasn't a polarizing issue in the America of 1963. But if a white politician in the Jim Crow South had married a black woman, the relationship would inevitably have been seen as a political gesture as well as a personal decision.

Today, we are less divided over race, but more divided over sex and reproduction. In a country that cannot agree whether fetuses are human beings, even questions like how to mourn and bury a miscarried child are inevitably freighted with ideological significance. Likewise, in a country where the majority of Down syndrome fetuses are aborted, the mere act of carrying a child with a genetic disorder to term — as both the Palins and the Santorums, whose daughter Bella has Trisomy 18, have done — feels like a political statement.

The same pattern holds with respect to politicians and their marriage vows. In an era that had a clear and stable understanding of marriage, it was easier to treat politicians' adulteries as a private matter between a husband and a wife. But hypocrisy is the tribute that vice pays to virtue, and a society that can't agree on the definition of sexual virtue inevitably takes a stronger interest in whether a politician actually lives up to the definition of marriage he defends.

When Sarah Palin wove special needs children into her 2008 speeches, or when Santorum featured his daughter Bella in a campaign video, they were implicitly acknowledging these personal-is-political realities. Likewise Mitt Romney, who ran an ad highlighting his 42-year marriage at the height of the twice-divorced Newt Gingrich's surge in the polls.

But by turning their personal choices to political ends, politicians lose the right to complain when those same personal lives are subject to partisan critiques. They can and should contest these critiques, but they can't complain about them. In a culture as divided about fundamental issues as our own, the kind of weird attacks that Rick Santorum is enduring come with the vocation he has chosen.